A reconciliation of the amounts included in the computation of earnings (loss) per common share, and diluted earnings (loss) per common share is as follows: | | | | | | | | | | | | | | | | | | Three Months Ended
September 30, | | Nine Months Ended
September 30, | In millions, except per share amounts | 2017 | | 2016 | | 2017 | | 2016 | Earnings (loss) from continuing operations | $ | 395 |
| | $ | 312 |
| | $ | 684 |
| | $ | 691 |
| Effect of dilutive securities | — |
| | — |
| | — |
| | — |
| Earnings (loss) from continuing operations – assuming dilution | $ | 395 |
| | $ | 312 |
| | $ | 684 |
| | $ | 691 |
| Average common shares outstanding | 412.9 |
| | 411.2 |
| | 412.6 |
| | 411.0 |
| Effect of dilutive securities | | | | | | | | Restricted stock performance share plan | 4.5 |
| | 4.1 |
| | 4.8 |
| | 4.5 |
| Average common shares outstanding – assuming dilution | 417.4 |
| | 415.3 |
| | 417.4 |
| | 415.5 |
| Basic earnings (loss) from continuing operations per common share | $ | 0.96 |
| | $ | 0.76 |
| | $ | 1.65 |
| | $ | 1.68 |
| Diluted earnings (loss) from continuing operations per common share | $ | 0.95 |
| | $ | 0.75 |
| | $ | 1.64 |
| | $ | 1.66 |
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